On Tue, Feb 26, 2019 at 07:18:00PM +0800, zhong jiang wrote: > From: zhongjiang <zhongjiang@xxxxxxxxxx> > > When soft_offline_in_use_page() runs on a thp tail page after pmd is plit, s/plit/split/ > we trigger the following VM_BUG_ON_PAGE(): > > Memory failure: 0x3755ff: non anonymous thp > __get_any_page: 0x3755ff: unknown zero refcount page type 2fffff80000000 > Soft offlining pfn 0x34d805 at process virtual address 0x20fff000 > page:ffffea000d360140 count:0 mapcount:0 mapping:0000000000000000 index:0x1 > flags: 0x2fffff80000000() > raw: 002fffff80000000 ffffea000d360108 ffffea000d360188 0000000000000000 > raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 > page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0) > ------------[ cut here ]------------ > kernel BUG at ./include/linux/mm.h:519! > > soft_offline_in_use_page() passed refcount and page lock from tail page to > head page, which is not needed because we can pass any subpage to > split_huge_page(). I don't see a description of what is going wrong and why change will fixed it. From the description, it appears as it's cosmetic-only change. Please elaborate. -- Kirill A. Shutemov
